Conversation naming (#8991)

Session renaming:
- `/rename my_session`
- `/rename` without arg and passing an argument in `customViewPrompt`
- AppExitInfo shows resume hint using the session name if set instead of
uuid, defaults to uuid if not set
- Names are stored in `CODEX_HOME/sessions.jsonl`

Session resuming:
- codex resume <name> lookup for `CODEX_HOME/sessions.jsonl` first entry
matching the name and resumes the session

---------

Co-authored-by: jif-oai <jif@openai.com>

codex-rs/protocol/src/protocol.rs

@@ -273,6 +273,11 @@ pub enum Op {
     /// to generate a summary which will be returned as an AgentMessage event.
     Compact,
 
+    /// Set a user-facing thread name in the persisted rollout metadata.
+    /// This is a local-only operation handled by codex-core; it does not
+    /// involve the model.
+    SetThreadName { name: String },
+
     /// Request Codex to undo a turn (turn are stacked so it is the same effect as CMD + Z).
     Undo,
 
@@ -735,6 +740,9 @@ pub enum EventMsg {
     /// Ack the client's configure message.
     SessionConfigured(SessionConfiguredEvent),
 
+    /// Updated session metadata (e.g., thread name changes).
+    ThreadNameUpdated(ThreadNameUpdatedEvent),
+
     /// Incremental MCP startup progress updates.
     McpStartupUpdate(McpStartupUpdateEvent),
 
@@ -2186,11 +2194,15 @@ pub struct SkillsListEntry {
 
 #[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
 pub struct SessionConfiguredEvent {
-    /// Name left as session_id instead of thread_id for backwards compatibility.
     pub session_id: ThreadId,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub forked_from_id: Option<ThreadId>,
 
+    /// Optional user-facing thread name (may be unset).
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    #[ts(optional)]
+    pub thread_name: Option<String>,
+
     /// Tell the client what model is being queried.
     pub model: String,
 
@@ -2226,6 +2238,14 @@ pub struct SessionConfiguredEvent {
     pub rollout_path: Option<PathBuf>,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize, JsonSchema, TS)]
+pub struct ThreadNameUpdatedEvent {
+    pub thread_id: ThreadId,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    #[ts(optional)]
+    pub thread_name: Option<String>,
+}
+
 /// User's decision in response to an ExecApprovalRequest.
 #[derive(Debug, Default, Clone, Deserialize, Serialize, PartialEq, Eq, Display, JsonSchema, TS)]
 #[serde(rename_all = "snake_case")]
@@ -2569,6 +2589,7 @@ mod tests {
             msg: EventMsg::SessionConfigured(SessionConfiguredEvent {
                 session_id: conversation_id,
                 forked_from_id: None,
+                thread_name: None,
                 model: "codex-mini-latest".to_string(),
                 model_provider_id: "openai".to_string(),
                 approval_policy: AskForApproval::Never,